To infer the behavior of a user, known technology uses outputs supplied from various types of sensors installed in a terminal apparatus carried by a user. For example, the current position of the user may thereby be located from positional information collected by a global positioning system (GPS) receiver, a motion sensor, or a radio frequency identification (RFID) tag. In another example, a travel track of the user may be identified by storing positional information in time series.
In addition to the above technology to infer the current position or travel track of the user, there is also technology that infers a direction of the user. An example of the technology that infers the direction of the user is a pedestrian navigation method that indicates a route to a destination or guides the pedestrian along the route according to the current position and direction of the pedestrian. This pedestrian navigation method hypothesizes the direction of the back or top of the mobile telephone as the direction of the pedestrian, assuming a situation in which the pedestrian manipulates a mobile telephone or views a display while holding the mobile telephone with a hand. Under this hypothesis, a pedestrian navigation server displays, on the mobile telephone, the direction toward and distance to the destination with respect to the current position, assuming that the mobile telephone direction measured by a magnetic direction sensor is an upward direction.
User's behavior inferred as described above is used for the user to navigate.
However, the above conventional technology infers the direction of the pedestrian only in a limited situation in which a route is indicated to the pedestrian or the pedestrian is guided along the route; the direction of the user may be inferred only when a relationship between the user and the terminal apparatus is known.
The mobile telephone is not used by the user at all times, or rather the mobile telephone is generally carried in a state in which the mobile telephone is stored in a bag, a pocket of clothes, or the like. When the mobile telephone is carried while in a bag or a pocket of clothes, the hypothesis in the above pedestrian navigation method that the pedestrian manipulates the mobile telephone or views a display while holding the mobile telephone with a hand does not hold. Thus, in the above pedestrian navigation method, the direction of the user may be inferred only when the relationship between the user and the terminal apparatus is known. For example, the terminal apparatus may also be used in monitoring to collect information about advertisements in which the user was interested during a travel. When a relationship between the user and the terminal apparatus is unknown, then it becomes hard to use the terminal apparatus to collect user's interest in advertisements. Japanese Laid-open Patent Publication No. 2002-58057 is an example of related art.